Introduction Follistatin (FST) is a protein with numerous biological roles and was recently identified as an exercise-inducible hepatokine; however, the signals that regulate this are not well understood. The purpose of this study was to delineate potential endocrine factors that may regulate hepatic FST at rest and during exercise.

Methods This study used four experiments. First, male and female C57BL/6J mice remained sedentary or were subjected to a single bout of exercise at moderate or exhaustive intensity with liver collected immediately post. Second, mice were injected with glucagon (1 mg·kg−1, 60 min), epinephrine (2 mg·kg−1, 30 min), glucagon then epinephrine, or saline. Third, mice were pretreated with propranolol (20–60 mg·kg−1, 30 min) before epinephrine injection. Fourth, glucagon receptor wild type (Gcgr+/+) or knockout (Gcgr−/−) mice were pretreated with saline or propranolol (20 mg·kg−1, 30 min) and were subjected to a single bout of exhaustive exercise with liver collected immediately post or after 2 h recovery. In all experiments liver FST mRNA expression was measured, and in experiment four FST protein content was measured.

Results A single bout of treadmill exercise performed at an exhaustive but not moderate-intensity increased FST expression, as did injection of glucagon or epinephrine alone and when combined. Pretreatment of mice with propranolol attenuated the epinephrine-induced increase in FST expression. The exercise-induced increase in FST expression was attenuated in Gcgr−/− mice, with no effect of propranolol. Gcgr−/− mice had higher protein content of FST, but there was no effect of exercise or propranolol.

Conclusions These data suggest that both glucagon and epinephrine regulate hepatic FST expression at rest; however, only glucagon is required for the exercise-induced increase.

IL-6 is secreted from muscles to the circulation during high-intensity and long-duration exercise, where muscle-derived IL-6 works as an energy sensor to increase release of energy substrates from liver and adipose tissues. We investigated the mechanism involved in the exercise-mediated surge in IL-6 during exercise. Using interval-based cycling in healthy young men, swimming exercise in mice, and electrical stimulation of primary human muscle cells, we explored the role of lactate production in muscular IL-6 release during exercise. First, we observed a tight correlation between lactate production and IL-6 release during both strenuous bicycling and electrically stimulated muscle cell cultures. In mice, intramuscular injection of lactate mimicked the exercise-dependent release of IL-6, and pH buffering of lactate production during exercise attenuated IL-6 secretion. Next, we used in vivo bioimaging to demonstrate that intrinsic intramuscular proteases were activated in mice during swimming, and that blockade of protease activity blunted swimming-induced IL-6 release in mice. Last, intramuscular injection of the protease hyaluronidase resulted in dramatic increases in serum IL-6 in mice, and immunohistochemical analyses showed that intramuscular lactate and hyaluronidase injections led to release of IL-6-containing intramyocellular vesicles. We identified a pool of IL-6 located within vesicles of skeletal muscle fibers, which could be readily secreted upon protease activity. This protease-dependent release of IL-6 was initiated by lactate production, linking training intensity and lactate production to IL-6 release during strenuous exercise.

The objectives of this study were to estimate the impact of chewing time on caffeine release from gum and to understand caffeine pharmacokinetics. Caffeine release increased with chewing time (2 min < 5 min

caffeine absorption occurs both through the oral mucosa and gastrointestinal tract. This is of practical relevance to maximise caffeine doses and to synchronise effort with peak caffeine concentration.

A Physiological Role of Inter-Organ Network between Gastrointestine and Skeletal Muscle on the Regulation of Skeletal Muscle Volume
Katsumasa Goto The FASEB Journal 1 Apr 2019Abstract Number:700.1

Several inter-organ networks have been proposed. In general, gastrointestinal hormone gastric inhibitory polypeptide (GIP), which is synthesized in and secreted from K cells, regulates nutrient absorption via inhibition of gastric contraction and acid secretion. GIP receptor On the other hand, GIPR expresses in not only a gastrointestinal tract but also β cells in the pancreas. Since GIP also modulates glucose metabolism via insulin synthesis and secretion, GIP is also a member of incretin. Recently, the expression of GIP is also confirmed in skeletal muscle. However, there is no evidence for the inter-organ network between gastrointestine and skeletal muscle. In the present study, we investigated a physiological role of the inter-organ network between gastrointestine and skeletal muscle via GIP. GIP stimulates myogenic differentiation of C2C12 cells. Expression of GIPR was observed in C2C12 myoblasts and myotubes. Knockdown of GIPR induced the down-regulation of Pax7 in C2C12 myoblasts. In addition, GIPR-knockdown-associated depression of myotube formation of C2C12 cells were observed. On the other hand, GIPR-knockdown stimulated proliferation of C2C12 myoblasts. Therefore, GIP-GIPR intracellular signal(s) might play a role in the regulation of skeletal muscle volume via the mediation of myogenic differentiative potential.

It has been reported that autophagy and endoplasmic reticulum (ER) stress response cause improved hindlimb motor function and reduced damage of axons in spinal cord injured animals, respectively. However, the effects of melatonin on neural reconstruction and motor recovery through regulation of ER stress response and autophagy have not been well described. Therefore, the purpose of this study is to elucidate the effects of melatonin treatment on neural reconstruction and motor recovery through regulation of ER stress response and autophagy.

To verify the effect of melatonin injection on post-SCI alterations regarding neural cells, autophagy, and ER stress response, we analyzed markers at protein level, and morphological changes. At day 3 after SCI, melatonin did not cause behavioral improvement (p

In conclusion, exogenous treatment of melatonin may result in neural reconstruction after SCI through regulating autophagy and ER stress response at the injured spinal segments.

Skeletal muscle atrophy increases the risk of morbidity and mortality during various pathological conditions. In males, a decrease in the production and/or bioavailability of androgens (termed hypogonadism) directly contributes to muscle atrophy during various pathological conditions. While it is known that androgens prevent muscle atrophy, the mechanism(s) by which androgens mediate this effect are largely undefined. Our laboratory previously showed that mitochondrial turnover is enhanced in the tibialis anterior (TA) muscle of mice by androgen deprivation induced by castration surgery, and the magnitude of turnover was related to the degree of muscle atrophy.

These data suggest that potentially dysfunctional mitochondria contribute to the muscle atrophy observed following androgen deprivation. To gain a better understanding of that factors that might contribute to changes in mitochondrial quality control during androgen deprived conditions, we subjected total RNA from the TA of sham and castrated mice to microarray analysis. This unbiased approach identified significant changes in expression of genes that comprise the core molecular clock. qRT-PCR confirmed that expression of Brain and Muscle Arntl 1 (Bmal1) was decreased, while expression of Period 1, Period 2, and Period 3 (Per1, 2, & 3) were increased in the TA of castrated mice. When measured across a diurnal cycle, the change in expression of Bmal1, Per1, and Per2 exhibited reduced amplitude under androgen-deprived conditions. Interestingly, strong relationships were observed between the castration-mediated changes of core clock components and the measures of mitochondrial turnover. Specifically, Bmal1 expression was directly related to BCL2/adenovirus E1B 19 kDA protein-interacting protein 3 (BNIP3) protein content (R2 = 0.88), and the expression of core clock components were also directly related to the content of various mitochondrial proteins.

Expression of core clock components were also related to the autophagy marker, p62, and the mass of the TA. Ex post facto analysis of the microarray also identified changes in genes regulating polyamine biosynthesis. As polyamines are known to alter core clock function, we determined whether androgen deprivation altered polyamine content. While castration did not alter Spermine content, there was a significant reduction in the content of Spermidine in the TA of castrated mice.

Overall, these data suggest that reduced Spermidine concentrations may contribute to alterations in the core molecular clock in the skeletal muscle under androgen-deprived conditions, which may in turn contribute to reduced mitochondrial quality control and subsequent muscle atrophy

Introduction
Accurate and precise measurements are vital in research. Discrepancies between the actual values and values measured by a device can have serious implications on the design and results of an experiment. Thus, it is critical to know what devices provide reliable values. The aim of this study was to compare four different devices commonly used to measure pH in the absence and presence of Bovine Serum Albumin (BSA).

Methods
A balanced salt solution (NaCl 119 mM, NaHCO3 24 mM, Glucose 5.5 mM, CaCa2 1.6 mM, KCl 4.7 mM, MgSO4 1.17 mM, NaPO4 1.18 mM) with or without 4% BSA was bubbled with different CO2 percentages (2.5%, 3.8%, 5%, 7.5 %, 10%), 30% O2 and N2 as the balance gas using a gas mixer. After a steady state pH was reached, judged by the pH probe, four samples were taken simultaneously, and 3 replicate measurements with each of the four devices were made. The devices used in this study were the ABL 80 FLEX (RADIOMETER, blood gas analyzer), VetScan i-STAT® 1, pH paper (Macherey-Nagel, pH range 6.4 – 8.0) and a pH probe (OAKTON®, pH700). Measured pH values were plotted against the expected pH values for a given concentration of CO2 according to the Henderson–Hasselbalch equation (pH = pKa + log10 ([A−]/[HA]). Linear regression ± SEM was done for each device with and without BSA and the coefficient of determination and regression coefficients were calculated. The mean and difference of each measurement by device were then calculated and used to create Bland-Altman plots (right lower corner in each panel) to assess the agreement of the measuring device with the expected pH.

ResultsExcept for the pH paper, all devices showed a strong agreement with the expected pH for each CO2 percentage. The addition of BSA to the solution resulted in a trend to more acidic readings and to be even more in agreement with the expected pH for all four devices.

Conclusion
The blood gas analyzer, i-STAT®, and pH probe all proved to be suitable devices for use in measuring the pH of a balanced salt solution in the chosen pH range. The pH paper appeared to be unsuitable to measure the pH within physiological ranges. Additionally, throughout all measurements, the solutions with 4% BSA tended to provide even more accurate values than the solutions without BSA.